When shutting down an outdoor pool for repair or at the end of the swimming season, it is important that water, dirt and/or debris not become entrapped or lodged within the skimmers which are strategically located about the side walls of the pool. The skimmers are disposed at a predetermined elevation so that, when the pool is properly filled and the water therein is at a specified level, the surface water will circulate through a primary inlet and filter unit provided in each skimmer before being returned to the pool. Thus, under normal operating conditions, the skimmer will help to maintain the water surface free of floating leaves, bugs and other debris.
In various geographical areas where the outdoor temperatures are sub-freezing for prolonged periods of time, it is important that ceratain precautionary steps be taken, other than heating the water continuously, to prevent cracks or other damage occurring in the walls or floor of the pool or in the various components comprising the water circulation system. One of the precautionary steps is to either completely empty the pool of water or lower the level of the water so that it is substantially below the primary inlets of the skimmers. The latter procedure is the preferred one as it avoids the possibility of the empty pool heaving due to the expansion of the ground circumjacent the pool. Where a substantial amount of water remains in the pool, but the level thereof is lowered, it is important that some means be provided which will compensate for the pressures which develop against the walls when a thick ice crust forms on the water surface. If some compensating means is not provided to relieve such pressure, the walls and floor of the pool are susceptible to cracking which becomes evident when thawing occurs and thus, might require extensive and costly repairs.
Heretofore, it was thought that the placement of floating logs or the like on the water surface would provide the necessary pressure relief when the ice crust was formed. However, such a practice was, and still is, wholly ineffective because such objects either rested upon the top of the crust or became solidly embedded within the crust itself and thus, did not compensate or equalize the pressure as it developed between the wall and crust. Besides being ineffective as a pressure equalizer, the logs were a nuisance to remove from the pool and store once the thaw was completed.
When winterizing the skimmers various techniques and devices have heretofore been utilized, such as placing a bottle filled with antifreeze in a blocking position with respect to the primary inlet port of the skimmer or securing some membrane over the inlet port. Such techniques and devices were undesirable for one or more of the following reasons: (a) oftentimes the bottle was not properly sized relative to the primary inlet port, thus, requiring caulking to prevent leakage around the bottle; (b) the bottle was susceptible to breakage when improperly handled or when improperly filled with antifreeze; (c) securing a membrane over the primary inlet port was an awkward, frustrating and time-consuming operation; and (d) the membrane was susceptible to tearing or being punctured.